Proposal of a numerical model to assess the whole-body vibration on drivers and comparison of evaluation methodologies of different standards
Cibele Rabassa Flores1; Prof. Dr. Letícia Fleck Fadel Miguel1
1 Federal University of Rio Grande do Sul
doi:10.20906/CPS/COB-2015-0944
Resumo
Recent changes in Brazilian legislation impose new requirements for assessing the level of occupational exposure to whole-body vibration (WBV). Since the publication of the Annex I to Regulatory Standard 09 (NR-09), the employer must assess or measure the square root of the sum of the squares (rms) (total value) of the frequency-weighted acceleration values (aren) and, also, the vibration dose value that represents the vector-sum over the three orthogonal axes (VDVR), defined in ISO 2631-1 (1997), over an eight-hour period. Due to these changes, Brazil adopted two exposure measures that are not used in European legislation or by the ACGIH (USA). According to European Directive 2002/44/EC, the exposure to vibration may be assessed using the highest root-mean-square value (A(8)), or the highest vibration dose value (VDV) of the frequency-weighted accelerations, over an eight-hour period. Within this context, this study evaluates the daily exposure of a bus driver to whole-body vibration, using the Brazilian and the European exposure measures, and compares them with the exposure limit values. To this end, the dynamic model of the bus is subjected to different road profiles, using the Power Spectral Density parameters presented in ISO 8608 (1995). The evaluation of occupational exposure using the single-axis measures is compared with the assessment using the multi-axis approach. The results show the importance of assessment made in compliance with the legal requirements, and the need to apply the provisions of the Regulatory Standard 09 during the design stage of new equipment, so that their users are exposed to lower levels of vibration. In addition to the health risks, the workers' exposure to vibration levels above the exposure limit values entails the payment of the insalubrity premium, with considerable financial consequences for companies using those equipment and vehicles.
Palavras-chave: Whole-body vibration; Road roughness; Compliance